Drive mechanisms for surgical instruments such as for use in robotic surgical systems

ABSTRACT

A gearbox assembly and surgical instrument including the same. The gearbox assembly includes a drive gear including a round gear and a lead screw such that a rotational input to the round gear rotates the lead screw. A first hub is threadingly engaged about the lead screw such that rotation of the lead screw translates the first hub. A second hub is spaced-apart from the first hub and engaged with a drive rod. A compression spring is disposed between the hubs. When a force acting against the drive rod is below a threshold, the rotational input translates the first hub, compression spring, second hub, and drive rod. When the force is equal to or above the threshold, the rotational input translates the first hub and compresses the compression spring against the second hub to maintain the second hub and drive rod in position.

BACKGROUND Technical Field

The present disclosure relates to surgical instruments and, morespecifically, to drive mechanisms for surgical instruments such as, forexample, for use in robotic surgical systems.

Background of Related Art

Robotic surgical systems are increasingly utilized in various differentsurgical procedures. Some robotic surgical systems include a consolesupporting a robotic arm. One or more different surgical instruments maybe configured for use with the robotic surgical system and selectivelymountable to the robotic arm. The robotic arm provides one or moreinputs to the mounted surgical instrument to enable operation of themounted surgical instrument.

The number, type, and configuration of inputs provided by the roboticarm of a robotic surgical system are constraints in the design ofsurgical instruments configured for use with the robotic surgicalsystem. That is, in designing a surgical instrument compatible formounting on and use with the robotic arm of a robotic surgical system,consideration should be taken in determining how to utilize theavailable inputs provided by the robotic arm to achieve the desiredfunctionality of the surgical instrument.

SUMMARY

As used herein, the term “distal” refers to the portion that is beingdescribed which is further from a surgeon, while the term “proximal”refers to the portion that is being described which is closer to asurgeon. The terms “about,” substantially,” and the like, as utilizedherein, are meant to account for manufacturing, material, environmental,use, and/or measurement tolerances and variations. Further, to theextent consistent, any of the aspects described herein may be used inconjunction with any or all of the other aspects described herein.

Provided in accordance with aspects of the present disclosure is agearbox assembly for a surgical instrument. The gearbox assemblyincludes a drive gear, a first hub, a second hub, a drive rod, and acompression spring. The drive gear includes a round gear configured toreceive a rotational input and a lead screw coupled to the round gearsuch that the rotational input to the round gear rotates the lead screw.The first hub is threadingly engaged about the lead screw such thatrotation of the lead screw translates the first hub therealong. Thesecond hub is spaced-apart from the first hub. The drive rod is engagedwith the second hub. The compression spring is disposed between thefirst and second hubs. When a force acting against translation of thedrive rod is below a threshold, the rotational input translates thefirst hub to, in turn, translate the compression spring to, in turn,translate the second hub and the drive rod. When the force actingagainst translation of the drive rod is equal to or above the threshold,the rotational input translates the first hub to, in turn, compress thecompression spring against the second hub while the second hub and driverod are maintained in position.

In an aspect of the present disclosure, an input gear disposed in meshedengagement with the round gear of the drive gear to provide therotational input to the round gear.

In another aspect of the present disclosure, an external input isprovided and an input shaft is operably coupled between the externalinput and the input gear such that rotational driving of the externalinput provides the rotational input to the round gear.

In another aspect of the present disclosure, the first hub is a distalhub and the second hub is a proximal hub. In such aspects, the externalinput may be disposed proximally of the proximal hub and the input gearmay be disposed distally of the distal hub.

In yet another aspect of the present disclosure, the drive rod extendscoaxially through at least one of or each of: the first hub, the secondhub, the compression spring, or the drive gear.

In still another aspect of the present disclosure, the first and secondhubs are coupled to one another to define a maximum distancetherebetween. The compression spring is partially compressed when thefirst and second hubs define the maximum distance therebetween.

In still yet another aspect of the present disclosure, at least oneguide bar is operably coupled between the first and second hubs. Theguide bar(s) defines first and second rims configured to interact withfirst and second shoulders of the first and second hubs, respectively,to define the maximum distance between the first and second hubs.

In another aspect of the present disclosure, the first hub is movedtowards the second hub when the compression spring is compressed againstthe second hub to reduce a distance between the first and second hubs.

In another aspect of the present disclosure, the drive rod is engagedwith the second hub via a lock plate defining a keyhole.

Also provided in accordance with aspects of the present disclosure is asurgical instrument including a housing, a shaft extending distally fromthe housing, an end effector assembly extending distally from the shaftand including first and second jaw members at least the first of whichis movable relative to the second from a spaced-apart position to anapproximated position to grasp tissue therebetween, and a gearboxassembly disposed within the housing. The gearbox assembly may beconfigured similarly to any of the aspects detailed hereinabove orotherwise herein such that when a force acting against movement of atleast the first jaw member towards the approximated position is below athreshold, the rotational input translates the first hub to, in turn,translate the compression spring to, in turn, translate the second huband the drive rod to move at least the first jaw member towards theapproximated position. When the force acting against movement of atleast the first jaw member towards the approximated position is equal toor above the threshold, the rotational input translates the first hubto, in turn, compress the compression spring against the second hubwhile the second hub, the drive rod, and at least the first jaw memberare maintained in position.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and features of the present disclosure are describedhereinbelow with reference to the drawings wherein like numeralsdesignate identical or corresponding elements in each of the severalviews.

FIG. 1 is a perspective view of a surgical instrument provided inaccordance with the present disclosure configured for mounting on arobotic arm of a robotic surgical system;

FIG. 2A is a front, perspective view of a proximal portion of thesurgical instrument of FIG. 1 with an outer shell removed;

FIG. 2B is a rear, perspective view of the proximal portion of thesurgical instrument of FIG. 1 with the outer shell removed;

FIG. 3 is a front, perspective view of the proximal portion of thesurgical instrument of FIG. 1 with the outer shell and additionalinternal components removed;

FIG. 4 is a schematic illustration of an exemplary robotic surgicalsystem configured to releasably receive the surgical instrument of FIG.1 ;

FIG. 5 is a front, perspective view of a jaw drive sub-assembly of thesurgical instrument of FIG. 1 ;

FIG. 6 is a rear, perspective view of the jaw drive sub-assembly of thesurgical instrument of FIG. 1 ;

FIG. 7 is an exploded, perspective view of the jaw drive sub-assembly ofthe surgical instrument of FIG. 1 ;

FIG. 8 is an enlarged, front perspective view of the area of detail “8”in FIG. 7 ;

FIG. 9 is an enlarged, rear perspective view of the area of detail “8”in FIG. 7 ;

FIG. 10 is an exploded, perspective view illustrating a drive rod andlock plate of the jaw drive sub-assembly of the surgical instrument ofFIG. 1 ;

FIG. 11 is an enlarged, perspective view of the area of detail “11” inFIG. 7 ;

FIG. 12 is a longitudinal, cross-sectional view taken along section line“12-12” of FIG. 1 ;

FIG. 13 is a longitudinal, cross-sectional view taken along section line“13-13” of FIG. 1 ;

FIG. 14 is a transverse, cross-sectional view taken along section line“14-14” of FIG. 3 ;

FIG. 15 is a transverse, cross-sectional view taken along section line“15-15” of FIG. 3 ;

FIG. 16 is a transverse, cross-sectional view taken along section line“16-16” of FIG. 12 ;

FIG. 17 is a transverse, cross-sectional view taken along section line“17-17” of FIG. 12 ;

FIG. 18 is a transverse, cross-sectional view taken along section line“18-18” of FIG. 12 ;

FIG. 19 is a transverse, cross-sectional view taken along section line“19-19” of FIG. 12 ;

FIG. 20 is a perspective view of a distal portion of the surgicalinstrument of FIG. 1 with the end effector assembly disposed in an openposition;

FIG. 21 is a longitudinal, cross-sectional view of another proximalportion of the surgical instrument of FIG. 1 illustrating the jaw drivesub-assembly transitioning the end effector assembly from the openposition towards a closed position;

FIG. 22 is a perspective view of the distal portion of the surgicalinstrument of FIG. 1 with the end effector assembly disposed in theclosed position; and

FIG. 23 is a longitudinal, cross-sectional view of the proximal portionof the surgical instrument of FIG. 21 illustrating the jaw drivesub-assembly with the end effector assembly in the closed position.

DETAILED DESCRIPTION

Referring to FIGS. 1-3 , a surgical instrument 10 provided in accordancewith the present disclosure generally includes a housing 20, a shaft 30extending distally from housing 20, and end effector assembly 40extending distally from shaft 30, and a gearbox assembly 100 disposedwithin housing 20 and operably associated with end effector assembly 40.Instrument 10 is detailed herein as an articulating electrosurgicalforceps configured for use with a robotic surgical system, e.g., roboticsurgical system 1000 (FIG. 4 ). However, the aspects and features ofinstrument 10 provided in accordance with the present disclosure,detailed below, are equally applicable for use with other suitablesurgical instruments and/or in other suitable surgical systems.

With particular reference to FIG. 1 , housing 20 of instrument 10includes first and second body portion 22 a, 22 b and a proximal faceplate 24 that cooperate to enclose gearbox assembly 100 therein.Proximal face plate 24 includes apertures defined therein through whichinputs 110-140 of gearbox assembly 100 extend. A pair of latch levers 26(only one of which is illustrated in FIG. 1 ) extending outwardly fromopposing sides of housing 20 and enable releasable engagement of housing20 with a robotic arm of a surgical system, e.g., robotic surgicalsystem 1000 (FIG. 4 ). An aperture 28 defined through housing 20 permitsthumbwheel 440 to extend therethrough to enable manual manipulation ofthumbwheel 440 from the exterior of housing 20 to, as detailed below,permit manual opening and closing of end effector assembly 40.

Shaft 30 of instrument 10 includes a distal segment 32, a proximalsegment 34, and an articulating section 36 disposed between the distaland proximal segments 32, 34, respectively. Articulating section 36includes one or more articulating components 37, e.g., links, joints,etc. A plurality of articulation cables 38, e.g., four (4) articulationcables, or other suitable actuators, extend through articulating section36. More specifically, articulation cables 38 are operably coupled todistal segment 32 of shaft 30 at the distal ends thereof and extendproximally from distal segment 32 of shaft 30, through articulatingsection 36 of shaft 30 and proximal segment 34 of shaft 30, and intohousing 20, wherein articulation cables 38 operably couple with anarticulation sub-assembly 200 of gearbox assembly 100 to enableselective articulation of distal segment 32 (and, thus end effectorassembly 40) relative to proximal segment 34 and housing 20, e.g., aboutat least two axes of articulation (yaw and pitch articulation, forexample). Articulation cables 38 are arranged in a generally rectangularconfiguration, although other suitable configurations are alsocontemplated.

With respect to articulation of end effector assembly 40 relative toproximal segment 34 of shaft 30, actuation of articulation cables 38 iseffected in pairs. More specifically, in order to pitch end effectorassembly 40, the upper pair of cables 38 are actuated in a similarmanner while the lower pair of cables 38 are actuated in a similarmanner relative to one another but an opposite manner relative to theupper pair of cables 38. With respect to yaw articulation, the rightpair of cables 38 are actuated in a similar manner while the left pairof cables 38 are actuated in a similar manner relative to one anotherbut an opposite manner relative to the right pair of cables 38.

Continuing with reference to FIG. 1 , end effector assembly 40 includesfirst and second jaw members 42, 44, respectively. Each jaw member 42,44 includes a proximal flange portion 43 a, 45 a and a distal bodyportion 43 b, 45 b, respectively. Distal body portions 43 b, 45 b defineopposed tissue-contacting surfaces 46, 48, respectively. Proximal flangeportions 43 a, 45 a are pivotably coupled to one another about a pivot50 and are operably coupled to one another via a cam-slot assembly 52including a cam pin slidably received within cam slots defined withinthe proximal flange portion 43 a, 45 a of at least one of the jawmembers 42, 44, respectively, to enable pivoting of jaw member 42relative to jaw member 44 and distal segment 32 of shaft 30 between aspaced-apart position (e.g., an open position of end effector assembly40) and an approximated position (e.g. a closed position of end effectorassembly 40) for grasping tissue “T” (FIGS. 20 and 22 ) betweentissue-contacting surfaces 46, 48. As an alternative to this unilateralconfiguration, a bilateral configuration may be provided whereby bothjaw members 42, 44 are pivotable relative to one another and distalsegment 32 of shaft 30.

In embodiments, longitudinally-extending knife channels 49 (only knifechannel 49 of jaw member 44 is illustrated; the knife channel of jawmember 42 is similarly configured) are defined through tissue-contactingsurfaces 46, 48, respectively, of jaw members 42, 44. In suchembodiments, a knife assembly including a knife tube 62 (FIGS. 12-15 )extending from housing 20 through shaft 30 to end effector assembly 40and a knife blade (not shown) disposed within end effector assembly 40between jaw members 42, 44 is provided to enable cutting of tissue “T”(FIGS. 20 and 22 ) grasped between tissue-contacting surfaces 46, 48 ofjaw members 42, 44, respectively. Knife tube 62 (FIGS. 12-15 ) isoperably coupled to a knife drive sub-assembly 300 of gearbox assembly100 (FIGS. 2A-2B) at a proximal end thereof to enable selectiveactuation thereof to, in turn, reciprocate the knife blade (not shown)between jaw members 42, 44 to cut tissue “T” (FIGS. 20 and 22 ) graspedbetween tissue-contacting surfaces 46, 48.

Referring still to FIG. 1 , a drive rod 484 is operably coupled tocam-slot assembly 52 of end effector assembly 40, e.g., engaged with thecam pin thereof, such that longitudinal actuation of drive rod 484pivots jaw member 42 relative to jaw member 44 between the spaced-apartand approximated positions. More specifically, urging drive rod 484proximally pivots jaw member 42 relative to jaw member 44 towards theapproximated position while urging drive rod 484 distally pivots jawmember 42 relative to jaw member 44 towards the spaced-apart position.However, other suitable mechanisms and/or configurations for pivotingjaw member 42 relative to jaw member 44 between the spaced-apart andapproximated positions in response to selective actuation of drive rod484 are also contemplated. Drive rod 484 extends proximally from endeffector assembly 40 through shaft 30 and into housing 20 wherein driverod 484 is operably coupled with a jaw drive sub-assembly 400 of gearboxassembly 100 (FIGS. 2A-2B) to enable selective actuation of end effectorassembly 40 to grasp tissue “T” (FIGS. 20 and 22 ) therebetween andapply a closure force within an appropriate jaw closure force range, asdetailed below.

Tissue-contacting surfaces 46, 48 of jaw members 42, 44, respectively,are at least partially formed from an electrically conductive materialand are energizable to different potentials to enable the conduction ofelectrical energy through tissue “T” (FIGS. 20 and 22 ) graspedtherebetween, although tissue-contacting surfaces 46, 48 mayalternatively be configured to supply any suitable energy, e.g.,thermal, microwave, light, ultrasonic, ultrasound, etc., through tissue“T” (FIGS. 20 and 22 ) grasped therebetween for energy-based tissuetreatment. Instrument 10 defines a conductive pathway (not shown)through housing 20 and shaft 30 to end effector assembly 40 that mayinclude lead wires, contacts, and/or electrically-conductive componentsto enable electrical connection of tissue-contacting surfaces 46, 48 ofjaw members 42, 44, respectively, to an energy source (not shown), e.g.,an electrosurgical generator, for supplying energy to tissue-contactingsurfaces 46, 48 to treat, e.g., seal, tissue “T” (FIGS. 20 and 22 )grasped between tissue-contacting surfaces 46, 48.

With additional reference to FIGS. 2A, 2B, and 3 , as noted above,gearbox assembly 100 is disposed within housing 20 and includes anarticulation sub-assembly 200, a knife drive sub-assembly 300, and a jawdrive sub-assembly 400. Articulation sub-assembly 200 is operablycoupled between first and second inputs 110, 120, respectively, ofgearbox assembly 100 and articulation cables 38 (FIG. 1 ) such that,upon receipt of appropriate inputs into first and/or second inputs 110,120, articulation sub-assembly 200 manipulates cables 38 (FIG. 1 ) toarticulate end effector assembly 40 in a desired direction, e.g., topitch and/or yaw end effector assembly 40.

Knife drive sub-assembly 300 is operably coupled between third input 130of gearbox assembly 100 and knife tube 62 (FIGS. 12-15 ) such that, uponreceipt of appropriate input into third input 130, knife drivesub-assembly 300 manipulates knife tube 62 (FIGS. 12-15 ) to reciprocatethe knife blade (not shown) between jaw members 42, 44 to cut tissue “T”(FIGS. 20 and 22 ) grasped between tissue-contacting surfaces 46, 48.

Jaw drive sub-assembly 400, as detailed below, is operably coupledbetween fourth input 140 of gearbox assembly 100 and drive rod 484 suchthat, upon receipt of appropriate input into fourth input 140, jaw drivesub-assembly 400 pivots jaw members 42, 44 between the spaced-apart andapproximated positions to grasp tissue “T” (FIGS. 20 and 22 )therebetween and apply a closure force within an appropriate closureforce range.

Gearbox assembly 100 is configured to operably interface with a roboticsurgical system 1000 (FIG. 4 ) when instrument 10 is mounted on roboticsurgical system 1000 (FIG. 4 ), to enable robotic operation of gearboxassembly 100 to provide the above-detailed functionality. That is,robotic surgical system 1000 (FIG. 4 ) selectively provides inputs toinputs 110-140 of gearbox assembly 100 to articulate end effectorassembly 40, grasp tissue “T” (FIGS. 20 and 22 ) between jaw members 42,44, and/or cut tissue “T” (FIGS. 20 and 22 ) grasped between jaw members42, 44. However, it is also contemplated that gearbox assembly 100 beconfigured to interface with any other suitable surgical system, e.g., amanual surgical handle, a powered surgical handle, etc. For the purposesherein, robotic surgical system 1000 (FIG. 4 ) is generally described.

Turning to FIG. 4 , robotic surgical system 1000 is configured for usein accordance with the present disclosure. Aspects and features ofrobotic surgical system 1000 not germane to the understanding of thepresent disclosure are omitted to avoid obscuring the aspects andfeatures of the present disclosure in unnecessary detail.

Robotic surgical system 1000 generally includes a plurality of robotarms 1002, 1003; a control device 1004; and an operating console 1005coupled with control device 1004. Operating console 1005 may include adisplay device 1006, which may be set up in particular to displaythree-dimensional images; and manual input devices 1007, 1008, by meansof which a person, e.g., a surgeon, may be able to telemanipulate robotarms 1002, 1003 in a first operating mode. Robotic surgical system 1000may be configured for use on a patient 1013 lying on a patient table1012 to be treated in a minimally invasive manner. Robotic surgicalsystem 1000 may further include a database 1014, in particular coupledto control device 1004, in which are stored, for example, pre-operativedata from patient 1013 and/or anatomical atlases.

Each of the robot arms 1002, 1003 may include a plurality of members,which are connected through joints, and mounted device which may be, forexample, a surgical tool “ST.” One or more of the surgical tools “ST”may be instrument 10 (FIG. 1 ), thus providing such functionality on arobotic surgical system 1000.

Robot arms 1002, 1003 may be driven by electric drives, e.g., motors,connected to control device 1004. Control device 1004, e.g., a computer,may be configured to activate the motors, in particular by means of acomputer program, in such a way that robot arms 1002, 1003, and, thus,their mounted surgical tools “ST” execute a desired movement and/orfunction according to a corresponding input from manual input devices1007, 1008, respectively. Control device 1004 may also be configured insuch a way that it regulates the movement of robot arms 1002, 1003and/or of the motors.

With reference to FIGS. 5-7 and 12-19 , jaw drive sub-assembly 400 ofgearbox assembly 100 is shown generally including an input shaft 410, aninput gear 420, a drive gear 430, a thumbwheel 440, a spring forceassembly 450, and a drive rod assembly 480.

Input shaft 410 includes a proximal end portion 412 operably coupled tofourth input 140 and a distal end portion 414 having input gear 420engaged thereon such that rotational input provided to fourth input 140drives rotation of input shaft 410 to, thereby, drive rotation of inputgear 420. Input gear 420 is disposed in meshed engagement with roundgear 432 of drive gear 430 such that rotation of input gear 420, e.g.,in response to a rotational input provided at fourth input 140, effectsrotation of drive gear 430 in an opposite direction (see FIG. 16 ).Thumbwheel 440 is also disposed in meshed engagement with round gear 432of drive gear 430 such that rotation of thumbwheel 440 effects rotationof drive gear 430 in an opposite direction, thus enabling manual drivingof drive gear 430 via manipulation of thumbwheel 440 (see FIG. 16 ).

Also referring to FIG. 11 , drive gear 430, as noted above, includes around gear 432. Drive gear 430 further includes a lead screw 434 fixedlyengaged, e.g., monolithically formed, with round gear 432 such thatrotation of round gear 432 effects similar rotation of lead screw 434.

With additional reference to FIGS. 8 and 9 , spring force assembly 450includes a proximal hub 452, a distal hub 454, a compression spring 456,and a spring washer 458. Spring force assembly 450 further includes apair of guide bars 470.

Proximal and distal hubs 452, 454 of spring force assembly 450 may beidentical components that are oriented, positioned, and/or coupled toother components differently, thus providing different functionalitywhile reducing the number of different parts required to bemanufactured. The features of proximal and distal hubs 452, 454 aredetailed below to the extent necessary to facilitate understanding ofthe present disclosure and, thus, although some features may be detailedwith respect to only one of the proximal or distal hub 452, 454 and thefunction associated therewith, similar features may be provided on theother of the proximal or distal hub 452, 454 without the associatedfunction. Alternatively, proximal and distal hubs 452, 454 may bemanufactured as different components.

Proximal and distal hubs 452, 454 of spring force assembly 450 eachinclude a body 461 defining a cavity 462 and a retainer guide 463extending radially outwardly from opposed sides of body 461. Eachretainer guide 463 defines a trough 464 and includes a shoulder 465extending into the respective trough 464. Proximal and distal hubs 452,454 are oppositely-oriented relative to one another such that the openends of cavities 462 face one another and such that the shoulder 465 ofeach pair of retainer guides 463 of proximal and distal hubs 452, 454face away from one another.

Proximal hub 452 further includes a transverse slot 466 definedtherethrough that is configured to receive lock plate 482 of drive rodassembly 480, as detailed below, to fix lock plate 482 and, thus, aproximal end portion of drive rod 484 relative to proximal hub 452 (seeFIGS. 18 and 19 ). Once engaged in this manner, drive rod 484 is lockedin position coaxially disposed through proximal hub 452, distal hub 454,compression spring 456, and drive gear 430.

Distal hub 454 defines a threaded central bore 468 through body 461thereof. Threaded central bore 468 receives lead screw 434 of drive gear430 therethrough in threaded engagement therewith such that rotation oflead screw 434 drives translation of distal hub 454 longitudinally alonglead screw 434.

Compression spring 456 is disposed between proximal and distal hubs 452,454 with a proximal portion thereof disposed within cavity 461 ofproximal hub 452 and a distal portion thereof disposed within cavity 461of distal hub 462. At least a portion of compression spring 456 isdisposed about and/or configured to receive a portion of lead screw 434of drive gear 430 therethrough. Spring washer 458 is positioned withincavity 461 of proximal hub 452 between proximal hub 452 and compressionspring 456, although other configurations are also contemplated.

Each guide bar 470 is slidably received within the troughs 464 of acorresponding pair of retainer guides 463 of proximal and distal hubs452, 454. Each guide bar 470 includes a pair of spaced-apart rims 472,474 engaged thereon that are configured to abut shoulders 465 of therespective retainer guides 463, thereby defining a maximum distancebetween proximal and distal hubs 452, 454. However, proximal and/ordistal hubs 452, 454 are permitted to slide along guide bars 470 towardsone another, as detailed below.

Referring to FIGS. 10 and 19 , in conjunction with FIGS. 5-7 , drive rodassembly 480 includes lock plate 482 and drive rod 484. Lock plate 482defines a central keyhole 485 and a pair of slots 486, e.g., arcuateslots, defined on a distal face of lock plate 482 on either side ofcentral keyhole 485. Lock plate 482 is configured for insertion throughtransverse slot 466 of proximal hub 452 and, once installed therein,portions of spring washer 458 are configured for receipt within slots486 to secure lock plate 482 in engagement within proximal hub 452.Spring washer 458 is maintained in position within slots 486 under thebias of compression spring 456 which, at the maximum distance betweenproximal and distal hubs 452, 454 (as set by rims 472, 474 of guide bars470 and shoulders 465 of retainer guides 463), is pre-compressed.

Drive rod 484, as noted above, includes a distal end portion operablycoupled to cam-slot assembly 52 of end effector assembly 40 (FIG. 1 ).Drive rod 484 extends proximally through shaft 30, housing 20, andgearbox assembly 100 (see FIGS. 1-3 ) and is engaged within lock plate482 at a proximal end portion of drive rod 484. More specifically, driverod 484 defines a waist 488 towards the proximal end thereof that isconfigured to lock in engagement within central keyhole 485 of lockplate 482, e.g., via longitudinal translation of drive rod 484 intocentral keyhole 485 until waist 488 is aligned with central keyhole 485,followed by transverse movement of drive rod 484 relative to lock plate482, to thereby fix the proximal end portion of drive rod 484 relativeto lock plate 482 and, thus, relative to proximal hub 452 due to theengagement of lock plate 482 within proximal hub 452.

Turning to FIGS. 3, 12-15, and 17 , knife drive sub-assembly 300includes an input shaft 310, an input gear 320, a central gear 330defining external threading and internal threading, and a lead screw340. Input shaft 310 extends parallel and offset relative to input shaft410 and includes a proximal end portion 312 operably coupled to thirdinput 130 of gearbox assembly 100 (FIGS. 2A and 2B) and a distal endportion 314 having input gear 320 engaged thereon such that rotationalinput provided to third input 130 drives rotation of input shaft 310 to,thereby, drive rotation of input gear 320. Input gear 320 is disposed inmeshed engagement with the external threading of central gear 330.Central gear 330 is coaxial with and positioned distally of drive gear430.

Lead screw 340 extends through central gear 330 and is threadinglyengaged with the internal threading thereof such that rotation ofcentral gear 330, e.g., in response to a rotational input provide tothird input 130, translates lead screw 340. Lead screw 340 is fixedlyengaged about a proximal end portion of knife tube 62 such thattranslation of lead screw 340 translates knife tube 62, e.g., to therebytranslate the knife blade (not shown) between jaw members 42, 44 (FIG. 1). Lead screw 340 and knife tube 62 are coaxially disposed about driverod 484.

Referring to FIGS. 5-7 and 20-23 , in use, jaw members 42, 44 areinitially disposed in the spaced-apart position (FIG. 20 ) and,correspondingly, proximal and distal hubs 452, 454 are disposed in adistal-most position such drive rod 484 is disposed in a distal-mostposition (see FIGS. 12-15 ). Further, in this position, compressionspring 456 is disposed in a least-compressed condition; although, asnoted above, even in the least-compressed condition, compression spring456 is partially compressed due to the retention of compression spring456 in a pre-compressed configuration between proximal and distal hubs452, 454.

In response to an input to close end effector assembly 40, e.g.,rotational input to fourth input 140 or a manual input to rotation wheel440, drive shaft 410 is rotated to thereby rotate input gear 420 which,in turn, rotates drive gear 430 such that distal hub 454 is translatedproximally towards proximal hub 452 (see FIG. 21 ). With reference toFIG. 21 , proximal translation of distal hub 454 urges distal hub 454against compression spring 456. Initially, where forces resistingapproximation of jaw members 42, 44 are below a threshold correspondingto the spring value of compression spring 456, the closure force appliedby jaw members 42, 44 is relatively low such that the urging of distalhub 454 proximally against compression spring 456 urges compressionspring 456 proximally which, in turn, urges lock plate 482 and, thus,drive rod 484 proximally to pivot jaw member 42 relative to jaw member44 from the spaced-apart position towards the approximated position tograsp tissue “T” therebetween (FIGS. 20 and 22 ).

Referring to FIGS. 5-7, 22, and 23 , upon further approximation of jawmembers 42, 44 to grasp tissue “T” therebetween, the forces resistingapproximation of jaw members 42, 44, e.g., tissue “T” resistingcompression, may reach the threshold and, thus the closure force appliedby jaw members 42, 44 may reach a corresponding threshold. In order tomaintain the closure force applied by jaw members 42, 44 within aclosure force range such as, for example, from about 3 kg/cm² to about16 kg/cm², application of further closure force by jaw members 42, 44 isinhibited beyond this point despite further rotational input to fourthinput 140. More specifically, and with reference to FIG. 23 , once thethreshold has been reached, further rotational input to fourth input 140rotates drive shaft 410, input gear 420, and drive gear 430 to translatedistal hub 454 further proximally into compression spring 456. However,rather than compression spring 456 urging proximal hub 452 furtherproximally to continue approximation of jaw members 42, 44 and increasethe closure force applied therebetween, compression spring 456 iscompressed, enabling proximal hub 452 and, thus, drive rod 484 to remainin position, thus inhibiting application of additional closure forcebetween jaw members 42, 44.

Referring to FIG. 22 , with tissue “T” grasped between jaw members 42,44 under an appropriate closure force, energy may be supplied to jawmembers 42, 44 to treat, e.g., seal tissue “T.” Thereafter, the knifeblade (not shown) may be advanced between jaw members 42, 44 to cut thetreated tissue “T.” With additional reference to FIGS. 14 and 17 , inorder to advance the knife blade (not shown), a rotational input isprovided to input 130 to drive rotation of input shaft 310, input gear320, and central gear 330, thereby translating lead screw 340 distallysuch that knife tube 62 is likewise translated distally to advance theknife blade (not shown) between jaw members 42, 44 to cut the treatedtissue “T.” Alternatively, tissue “T” may be cut without first treatingthe tissue “T” and/or tissue “T” may be treated without subsequentcutting.

Once tissue “T” is cut, an opposite rotation input is provided to input130 to return the knife blade (not shown) to its initial positionproximally of body portions 43 b, 45 b of jaw members 42, 44 (see FIG. 1). Thereafter, an opposite input is provided to input 140 (or rotationwheel 440) to return jaw members 42, 44 back towards the spaced-apartposition to release the sealed and/or cut tissue.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplifications of variousembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended thereto.

The invention claimed is:
 1. A gearbox assembly for a surgicalinstrument, comprising: a drive gear including a lead screw, the drivegear configured to receive a rotational input to rotate the lead screw;a first hub threadingly engaged about the lead screw such that rotationof the lead screw translates the first hub therealong, the first hubincluding a first retainer guide; a second hub axially aligned with, andspaced-apart from, the first hub, the second hub including a secondretainer guide; a guide bar slidably received within the first andsecond retainer guides of the first and second hubs; a drive rod engagedwith the second hub; and a compression spring disposed between the firstand second hubs, at least a portion of the compression spring disposedaround a portion of the lead screw, wherein, when a force acting againsttranslation of the drive rod is below a threshold, the rotational inputtranslates the first hub to, in turn, translate the compression springto, in turn, translate the second hub and the drive rod, and wherein,when the force acting against translation of the drive rod is equal toor above the threshold, the rotational input translates the first hubto, in turn, compress the compression spring against the second hubwhile the second hub and drive rod are maintained in position.
 2. Thegearbox assembly according to claim 1, wherein the drive gear furtherincludes a round gear coupled to the lead screw such that the rotationalinput is received by the round gear to rotate the lead screw, andfurther comprising an input gear disposed in meshed engagement with theround gear of the drive gear to provide the rotational input to theround gear.
 3. The gearbox assembly according to claim 2, furthercomprising an external input and an input shaft interconnecting theexternal input and the input gear such that rotational driving of theexternal input rotates the input shaft and the input gear to provide therotational input to the round gear.
 4. The gearbox assembly according toclaim 3, wherein the first hub is a distal hub and the second hub is aproximal hub, the external input disposed proximally of the proximal huband the input gear disposed distally of the distal hub.
 5. The gearboxassembly according to claim 1, wherein the drive rod extends coaxiallythrough at least one of: the first hub, the second hub, the compressionspring, or the drive gear.
 6. The gearbox assembly according to claim 1,wherein the drive rod extends coaxially through each of: the first hub,the second hub, the compression spring, and the drive gear.
 7. Thegearbox assembly according to claim 1, wherein the guide bar definesfirst and second rims configured to interact with first and secondshoulders of the first and second retainer guides, respectively, todefine the maximum distance between the first and second hubs.
 8. Thegearbox assembly according to claim 1, wherein the compression spring ispartially compressed when the first and second hubs define maximumdistance therebetween, and the first hub is moved towards the second hubwhen the compression spring is compressed against the second hub toreduce a distance between the first and second hubs.
 9. The gearboxassembly according to claim 1, wherein the drive rod is engaged with thesecond hub via a lock plate defining a keyhole.
 10. The gearbox assemblyaccording to claim 1, further including an articulation subassemblydisposed distal to the lead screw.
 11. A surgical instrument,comprising: a housing; a shaft extending distally from the housing; anend effector assembly extending distally from the shaft, the endeffector assembly including first and second jaw members, at least thefirst jaw member movable relative to the second jaw member from aspaced-apart position to an approximated position to grasp tissuetherebetween; and a gearbox assembly disposed within the housing, thegearbox assembly including: a drive gear including a lead screw, thedrive gear configured to receive a rotational input to rotate the leadscrew; a first hub threadingly engaged about the lead screw such thatrotation of the lead screw translates the first hub therealong, thefirst hub including a first retainer guide; a second hub axially alignedwith, and spaced-apart from, the first hub, the second hub including asecond retainer guide; a guide bar slidably received within the firstand second retainer guides of the first and second hubs; a drive rodengaged with the second hub at a proximal end portion thereof andoperably coupled to the end effector assembly at a distal end portionthereof such that translation of the drive rod moves at least the firstjaw member from the spaced-apart position towards the approximatedposition; and a compression spring disposed between the first and secondhubs, at least a portion of the compression spring disposed around aportion of the lead screw, wherein, when a force acting against movementof at least the first jaw member towards the approximated position isbelow a threshold, the rotational input translates the first hub to, inturn, translate the compression spring to, in turn, translate the secondhub and the drive rod to move at least the first jaw member towards theapproximated position, and wherein, when the force acting againstmovement of at least the first jaw member towards the approximatedposition is equal to or above the threshold, the rotational inputtranslates the first hub to, in turn, compress the compression springagainst the second hub while the second hub, the drive rod, and at leastthe first jaw member are maintained in position.
 12. The surgicalinstrument according to claim 11, wherein the drive gear furtherincludes a round gear coupled to the lead screw such that the rotationalinput is received by the round gear to rotate the lead screw, and thegearbox assembly further comprises an input gear disposed in meshedengagement with the round gear of the drive gear to provide therotational input to the round gear.
 13. The surgical instrumentaccording to claim 12, wherein the gearbox assembly further comprises anexternal input and an input shaft disposed within the housing, the inputshaft operably coupled between the external input and the input gearsuch that rotational driving of the external input provides therotational input to the round gear.
 14. The surgical instrumentaccording to claim 13, wherein the first hub is a distal hub and thesecond hub is a proximal hub, the external input disposed proximally ofthe proximal hub and the input gear disposed distally of the distal hub.15. The surgical instrument according to claim 11, wherein the drive rodextends coaxially through at least one of: the first hub, the secondhub, the compression spring, or the drive gear.
 16. The surgicalinstrument according to claim 11, wherein the drive rod extendscoaxially through each of: the first hub, the second hub, thecompression spring, and the drive gear.
 17. The surgical instrumentaccording to claim 11, wherein the guide bar defines first and secondrims configured to interact with first and second shoulders of the firstand second retaining guides, respectively, to define a maximum distancebetween the first and second hubs.
 18. The surgical instrument accordingto claim 11, wherein the compression spring is partially compressed whenthe first and second hubs define a maximum distance therebetween, andthe first hub is moved towards the second hub when the compressionspring is compressed against the second hub to reduce a distance betweenthe first and second hubs.
 19. The surgical instrument according toclaim 11, wherein the drive rod is engaged with the second hub via alock plate defining a keyhole.
 20. The surgical instrument according toclaim 11, wherein the shaft includes a proximal segment, a distalsegment, and an articulating section disposed between the proximal anddistal segments, and the gearbox assembly includes an articulationsubassembly configured to enable selective articulation of the distalsegment of the shaft.